A sweetener containing glycosylfructosides, such as glocosylsucrose, maltasylsucrose and maltotriosylsucrose, wherein glocosyl groups having a glucose polymerization degree of 2-4 or higher are bound to fructose residues via fructosyl linkage, has been commercialized by Hayashibara Co., Ltd., Okayama, Japon, under the Registered Trademark of "Coupling Sugar".
This sweetener with a mild sweetness has been used widely to sweeten food products and to impart thereto an appropriate viscosity, moisture and/or gloss, as well as to prevent the crystallization of sucrose in food products.
One advantage of this sweetener is that, unlike sucrose, it is usable as low-cariogenic sweetener because of its less tendency of forming water-insoluble glucan and lactic acid by cariogenic microorganism, while, like sucrose, it imparts an appropriate body to food products, as well as being digested, absorbed and metabolized into calorie.
As regards to the production of the glycosylfructoside sweetener, several procedures are known: For example, Japan Patent publication No. 40,949/74, Japan Patent Publication No.17,660/74, Japan Patent Publication No.22,520/81, and Japan Patent Kokai No.47,929/77 describe a procedure which comprises subjecting an aqueous solution containing sucrose and either starch or a partial starch hydrolysate to the action of cyclodextrin glucanotransferase enzyme (EC 2.4.1.19) or .alpha.-amylase (EC 3.2.1.1). Japan Patent Publication No.58,905/82 describes another procedure which comprises subjecting an aqueous solution containing sucrose and/or raffinose, and an aldooligosaccharide such as maltose, isomaltose, kojibiose, rhaminalibiose, isomaltotriose, panose or isopanose, to levansucrase enzyme (EC 2.4.1.10). In addition, a procedure wherein an aqueous solution containing sucrose, and either a maltooligosaccharide such as maltose, maltotriose and maltotetraose, or a starch hydrolysate having a Dextrose Equivalent (DE) of about 10-70 is subjected to a glocosyltransferase enzyme such as .alpha.-glucosidase (EC 3.2.1.20) is known.
Further studies on the components of the glycosylfructoside sweetener so obtained confirmed that oligoglucosylfructosides having a glucose polymerization degree of 2 or 3 are superior in sweetening power to polyglucosylfructosides with a glucose polymerization degree of 4 or higher, and that these oligoglucosylfructosides are suitable as low- or anti-cariogenic sweetener since, in comparison with sucrose, they form much less water-insoluble glucan and lactic acid when exposed to the action of cariogenic microorganism.
Also was confirmed that the oligoglucosylfructoside contents in the glycosylfructoside sweeteners produced with the conventional procedures are, however, from 10% to at most 50%.
Although several purification procedures, e.g. paper-chromatographic fractionation or selective adsorption and desorption using activated carbon, have been attempted to recover the oligoglucosylfructoside from such saccharide mixture, these procedures render the production of highpurity oligoglucosylfructosides on an industrial-sacle extremely very difficult.